Motion and forces GapFill

All measurements can be categorised as either  vectorstensorsscalarsholors (which have size but not direction) or  vectorsholorstensorsscalars (which have both size and direction), which include forces.

Distance is how far an object moves, and does not take into account direction.  VelocityMomentumDisplacementInertia is how far away from a starting position an object has travelled, and in which direction; it is a vector. Similarly,  inertiavelocitydisplacementmomentum is the speed of an object, taking into account the direction of travel; this is also a vector.  AccelerationVelocityMomentumInertia is another vector, and describes the rate at which an object speeds up or slows down. Newton's laws describe how forces affect motion.

Newton's first law states that if an object has no forces acting on it, it will  remain at the same velocitybe stationaryspeed upslow down. Newton's second law can be stated by the equation  force = mass ÷ accelerationforce = mass ÷ velocityforce = mass × accelerationforce = ½ mass × velocity².

Newton's third law states that when two objects interact,  a non-contact force is producedfriction causes them to heat upone exerts a larger force on the otherthey each exert opposite and equal forces on the other. 

Gravity is the attraction of objects to each other; it's responsible for a wide variety of effects, from making sure you stay on the ground to controlling the orbits of planets around the Sun.  InertiaWeightNewtonMass is the name given to the gravitational attraction between an object and a planet (usually Earth), which acts from a point on an object known as its  centre of kilogramcentre of masscentre of newtoncentre of weight, and can be measured using a device called   an inertiametera weightmetera kilogrammetera newtonmeter.

Forces are very important when discussing vehicle safety. The distance that a vehicle travels before coming to a stop is called its stopping distance, which is equal to  thinking distance + braking distancebraking distance – thinking distancethinking distance – braking distancebraking distance × thinking distance. Thinking distance is the distance travelled by a vehicle before the driver reacts to a hazard or other signal. Braking distance is the distance travelled by a vehicle while its brakes are applied, before it comes to a complete stop. Thinking distance and reaction time can be affected by factors such as  distractions, alcohol or tirednessroad conditions, car speed or worn tyresroad quality, car size or alcoholage, alcohol or road quality. Braking distance can be affected by factors such as  distractions, alcohol, tiredness or car speedthe weather, car speed, or quality of brakes and tyresage, alcohol or road qualityroad quality, car size or alcohol.